System users interact and communicate using various types of devices such as desktop computers, laptop computers, personal digital assistants, desktop phones, cell phones, and other devices. Systems and methods have been developed to determine whether certain system users are connected to a network and available for communication through one or more of those network devices. Generally, knowledge of a system user's network status and availability is referred to as “presence.”
Presence information can be exchanged between users in different systems or domains. When a user changes their state, a notification is sent to the user desiring to receive presence information. If a system includes many users that subscribe to receive presence information from a single user, the same presence information notifications are sent continuously to a server that manages the users desiring to receive the presence information. The continuous passing of presence information results in significant system overhead.